I think I am going to go with my string idea. Use the clips as anchor points. Run string across the insulation from anchor point to a anchor point on the opposite side. That will form a web to hold the insulation up. Then go over it and add a drop of super glue wherever the string intersects. That will bind it all together and distribute the load across the whole web.
Be a couple of days before I can try this. Lower back is killing me from too much lifting and moving stuff around. Will post pictures when I get to it.